In the design of electronic circuits for various applications, thermal monitoring is used, and can be critical for semiconductor components such as integrated circuits to avoid higher temperatures that could negatively affect various circuit components. Temperature monitoring may be used for a variety of applications such as radar, which can carry operating temperatures in a range of −40° to 150° Celsius. Integrated temperature sensors often use an architecture based on diodes and use ΔVBE (delta base-emitter voltage) measurements between a pair of bipolar junction transistors to define a voltage that is proportional to absolute temperature (PTAT).
To obtain good accuracy, prior art designs can require large calibration algorithms using at least two or three temperature insertion points to calibrate a temperature sensor. To increase the dynamic range on ΔVBE in technology areas such as radar applications, higher numbers of diodes are used which can lead to complexity of circuits and inaccuracy of a temperature sensor. When using a high number of diodes, mismatch modeling is difficult and not very accurate.
Examples of circuitry where temperature monitoring is used include an all-digital phase locked loop (ADPLL) having components such as a time to digital converter (TDC) or digital controlled oscillator (DCO) that may exhibit some drift in temperature during use. This drift may give rise to parametric issues including drift or spurs at the output. Early detection of possible overheating can prevent system malfunctioning such as parameter degradation and irreversible damage. Effective and accurate temperature sensor calibration may be used to ensure early detection.
In previous circuit designs, to achieve a good accuracy, very large calibration algorithms have been required using at least two, three, or more temperature insertion points.